A “hospital-acquired infection” is a localized or systemic condition that results from an adverse reaction to the presence of an infectious agent(s) or its toxin(s) and that was not present or incubating at the time of admission to the hospital. Hospital-acquired infections affect about 2,000,000 patients per year in the U.S., causing about 90,000 deaths. They are the fourth leading cause of death in the U.S., behind only cancer, strokes, and heart disease. In addition to their human toll, each infection costs nearly $14,000 to treat, totaling $28 B each year in the U.S.
Consumers, employers, hospital insurers, regulatory agencies and others wish to know how many infections occur and how many people acquire an infection occur each year in a given hospital. However, few hospitals can answer these questions.
The current state of the art for identifying hospital-acquired infections is advanced by the Centers for Disease Control and Prevention (CDC) through its National Nosocomial Infection Surveillance (NNIS) program. Under NNIS, there are 13 major site categories and 48 specific sites or types of infection for which criteria have been developed, (Garner et al., APIC Infection Control and Applied Epidemiology: Principles and Practice, 1996). The method requires specially trained hospital clinical personnel to manually review clinical and other data for each patient, including patient admission, transfer and discharge data, laboratory results, pharmacy data, radiology data, physician notes, and nursing notes for each patient.
Here is an example of one of the forty-eight infection criteria:
DEFINITION: Other infections of the urinary tract must meet at least one of the following criteria:
Criterion 1: Patient has organisms isolated from culture of fluid (other than urine) or tissue from affected site.
Criterion 2: Patient has an abscess or other evidence of infection seen on direct examination, during a surgical operation, or during a histopathologic examination.
Criterion 3: Patient has at least two of the following signs or symptoms with no other recognized cause: fever (>38° C.), localized pain, or localized tenderness at the involved site and at least one of the following:
a) Purulent drainage from affected site;
b) Organisms cultured from blood that are compatible with suspected site of infection;
c) radiographic evidence of infection, e.g., abnormal ultrasound, CT scan, magnetic resonance imaging (MRI), or radiolabel scan (gallium, technetium);
d) Physician diagnosis of infection of the kidney, ureter, bladder, urethra, or tissues surrounding the retroperitoneal or perinephric space; or
e) Physician institutes appropriate therapy for an infection of the kidney, ureter, bladder, urethra, or tissues surrounding the retroperitoneal or perinephric space.
    This current state of the art for identifying hospital-acquired infections is a manual process that is so time consuming that no hospital has the personnel required to apply it to all patients in the hospital. Each patient admission requires at least 20 minutes to determine if a hospital-acquired infection was present, (Gavin P J, et al., SHEA 2004). At that rate, a hospital with 20,000 yearly admissions would require five full time trained reviewers just to measure the hospital's infection rate. Very few hospitals have this level of staffing for Infection Control.
In response to the lack of resources required to apply the NNIS method to all patients within most hospitals, the NNIS program eliminated the “hospital-wide component” (the calculation of the incidence of hospital-acquired infections throughout the hospital) in January 1999, (National Nosocomial Infections Surveillance (NNIS) System Report. Am J Infect Control 1999). As a result, most hospitals only identify certain infections in a subset of patients at certain times of the year. With this limited perspective, hospitals cannot determine the full extent of the problem of hospital-acquired infections nor its financial impact.
Moreover, the current manual process includes many criteria that require the subjective judgment of hospital clinical staff. In the 20+ years that the NNIS method has been used, there has been only one study regarding its objectivity, (Emori, et al., Infect Control Hosp Epidemio.l 1998). That study compared the number of infections reported from the same 1,136 patient charts when reviewed by three groups: NNIS participating hospitals, CDC-trained expert reviewers and CDC epidemiologists. The number of infections found by the three groups looking at the same 1,136 patient charts were 611, 1264 and 865, respectively. Moreover, many wish to compare the infection rates of several hospitals. However, this lack of objectivity makes such comparisons unreliable.